text model comparison
Claude Opus 5.5 vs Kimi K3
Claude Opus 5.5 and Kimi K3 are both current text models, from Anthropic and Moonshot Kimi. Kimi K3 is 25% cheaper per 1M input tokens than Claude Opus 5.5, $3 vs $4. On Arena Text, Claude Opus 5.5 scores 1507 Elo and Kimi K3 1488 Elo (Arena, measured October 8, 2026). Both accept about 1.05M tokens of context (1,048,576 and 1,000,000).
Data verified October 12, 2026 · Dataset 2026-10-12
Side by side
Standard-tier prices in effect today. The better value in each row is highlighted.
| Fact | Claude Opus 5.5 | Kimi K3 |
|---|---|---|
| Price per 1M input tokens | $4 | $3 (better) |
| Price per 1M output tokens | $20 | $15 (better) |
| Cost of 10M input and 2M output tokens | $80 | $60 (better) |
| Arena Text | 1507 Elo (#1 of 39) (better) | 1488 Elo (#7 of 39) |
| GPQA Diamond | 90.6% (#22 of 37) | 93.1% (#15 of 37) (better) |
| FrontierMath Tiers 1-3 (v2) | 91.2% (#3 of 37) (better) | 72.2% (#19 of 37) |
| SimpleQA Verified | 72.2% (#4 of 34) (better) | 50.6% (#18 of 34) |
| Provider | Anthropic | Moonshot Kimi |
| Release date | September 22, 2026 | July 16, 2026 |
| Access | API only | API and open weights |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | Not reported |
| Input | text, image | text, image |
| Output | text | text |
When to choose each
Claude Opus 5.5
Best for
- Long-running agentic coding and knowledge work as the general-purpose default
- Cache-heavy agent loops where the 0.05x read multiplier compounds
Watch out for
- The API effort default is medium here, not high as on Claude Fable 5.1 and Claude Sonnet 5.5, so a like-for-like comparison has to set effort explicitly
- The 4.7-generation tokenizer produces roughly 30% more tokens for the same text than Claude Sonnet 4.6 and earlier, so per-token rates do not compare directly across generations
Kimi K3
Best for
- Teams that want a frontier-scale model they can also self-host, with one architecture across both paths
- Long-context work at mid-tier hosted pricing
Watch out for
- Hosted rates match Claude Sonnet 5 exactly at $3 / $15 while offering a larger context window, so the comparison turns on capability rather than price
- Running the open weights shifts cost to infrastructure, which the token rates recorded here do not represent
- Moonshot’s self-reported results place it ahead of Claude Opus 4.8 and GPT-5.5 but behind Claude Fable 5 and GPT-5.6 Sol; none of this was reproduced independently here
Claude Opus 5.5 vs Kimi K3 FAQ
Which is cheaper, Claude Opus 5.5 or Kimi K3?
Kimi K3 is 25% cheaper per 1M input tokens than Claude Opus 5.5, $3 vs $4. For 10M input and 2M output tokens, Claude Opus 5.5 costs $80 and Kimi K3 $60 at standard rates.
Which scores higher on independent benchmarks, Claude Opus 5.5 or Kimi K3?
Claude Opus 5.5 leads on Arena Text, 1507 Elo to 1488 Elo; Kimi K3 leads on GPQA Diamond, 93.1% to 90.6%; Claude Opus 5.5 leads on FrontierMath Tiers 1-3 (v2), 91.2% to 72.2%. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, Claude Opus 5.5 or Kimi K3?
Both accept about 1.05M tokens of context (1,048,576 and 1,000,000).
Can I run Claude Opus 5.5 or Kimi K3 myself?
Kimi K3 is released as open weights you can run yourself; Claude Opus 5.5 is available through its provider's API only.
Related comparisons
- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Fable 5 vs Claude Opus 5.5
- Claude Opus 4.8 vs Claude Opus 5.5
- Claude Opus 4.8 vs Kimi K3
- Claude Opus 5.5 vs Gemini 3.8 Flash
- Claude Opus 5.5 vs GPT-5.5
- Claude Opus 5.5 vs GPT-5.6 Sol
- Claude Opus 5 vs Claude Opus 5.5
- Claude Opus 5 vs Kimi K3
- Gemini 3.8 Flash vs Kimi K3
Production evaluation
Choosing between Claude Opus 5.5 and Kimi K3?
Public benchmarks narrow the shortlist. We run both on your own tasks, data and cost limits, then build the routing and review controls to run the winner in production.
- A head-to-head evaluation on your real workload
- Routing between models by cost and difficulty